Maybe evidence to back up the claim will eventually be produced. But, as it stands, the account rings too many discordant bells to be taken at face-value.

Similarly with the story of Iman al-Obeidi, who burst into a hotel in Tripoli in March shouting that she'd been gang-raped by Gaddafi's soldiers.

Dragged away by government officials, she turned up a few days later in Tunisia, then, after a further few days, in Qatar.

Last week, Ms Al-Obeidi arrived in Timosara in Romania in the company of officials of the UN High Commission for Refugees. Apparently, she had been deported from Qatar to Benghazi and from there had travelled to Romania via Malta and Italy. Associated Press reported that she now hopes to make a new life in the US.

Again, every detail of the story she has told may be true. But the detail which hasn't been supplied - the circumstances of her deportation from Qatar, for example - give reason for doubt.

It's not that the idea of rape as a weapon of war is implausible. Hundreds of thousands of Ukrainian, Polish and most of all German women were raped by Red Army soldiers as they advanced through eastern Europe in 1944/45. The Japanese army raped its way across Korea. The Americans, in their turn, raped a multitude of women after taking Japan.

Channel 4 will tonight broadcast Sri Lanka's Killing Fields, showing both Sinhalese and Tamil soldiers displaying photographs and film of the corpses of women they'd raped and then murdered.

Joshua Phillips's None Of Us Were Like This Before, published last year, describes how the requirements of war in Iraq and Afghanistan turned American boys into sex-depraved savages.

Pakistani soldiers are said to have raped 200,000 Bengali women during the violence accompanying the secession of Bangladesh in 1971. Turkish soldiers were accused of the mass rape of Greek-Cypriot women after the invasion of 1974.

Amnesty estimates that up to half-a-million women were raped during the Rwandan genocide of 1994. The Burmese army is said to have raped tens of thousands of Rohingya Muslim women in 1992 and then to have driven them out of the country to Bangladeshi refugee camps.

On August 27 last year, Amnesty pleaded for action following 'the latest reports of mass rape and other sexual violence committed in the Walikale region of North Kivu, Democratic Republic of Congo (DRC) between 30th July and 2nd August ... More than 150 civilians in 13 villages were raped by members of armed groups ... including the government forces that the United Nations is supporting.'

So, why not British soldiers? The feminist campaigner and literary critic Germaine Greer was roundly denounced for making this point on Question Time last Thursday: "Rape is always present where you have slaughter ... All soldiers, in certain circumstances, will rape, regardless of whether they're ours, or theirs, or whose."

The loudest response has been of abuse being piled on Ms Greer's head. How dare she say these terrible things about our boys? Atrocities are perpetrated by our enemies - not by us.

In this perspective, it's not the phenomenon of mass-rape for military purposes which deserves scrutiny, but the extent to which it can be used for propaganda purposes against the enemy du jour.

The propagandists may already be celebrating their latest success. Distress and anger arising from the rape stories has helped shift discussion of the Libyan conflict away from the question of whether the Nato assault can be justified towards an assumed moral imperative to oust, or kill, Gaddafi.

UN Resolution 1973 authorises all necessary measures to protect Libyan civilians. The bombing of recent weeks has gone far beyond this. Now Obama, Cameron and Sarkozy talk openly of further extending their war aims.

Last Wednesday, Nato defence ministers met in Brussels to discuss the state of the Libyan campaign. Agency reports afterwards suggested that the US, Britain and France had not been entirely successful in persuading Germany, Poland, the Netherlands, Spain and Turkey to throw themselves fully behind the drive for regime change.

Perhaps the Gaddafi-in-Viagra-rape-horror story will help bring them round. Meanwhile, hard evidence of the mass-rape of women in the Congo continues to mount.